1. Field of the Invention
The present invention relates to the field of angioplasty and, in particular, to an imaging catheter for insertion into a patient's vascular system to record and remember the configuration or shape of an obstruction therein.
2. Description of the Prior Art
Angioplasty has gained wide acceptance in recent years as an efficient and effective method for treating certain types of vascular diseases. In particular, angioplasty is widely used for expanding a constricted area or a lesion in a coronary artery. It is also used for treatment of lesions in other parts of the vascular system as well.
The most widely used form of angioplasty makes use of a balloon dilatation catheter which is introduced into a patient's vascular system and is positioned across a stenosis. The balloon is inflated by supplying fluid under pressure through an inflation lumen connected to the balloon. The inflation of the balloon imparts a stretching force to the stenosis or artery wall to reestablish an acceptable blood flow through the artery.
However, balloon dilatation is not always the method of choice for treating a stenosis within a coronary artery. Depending on the nature of the obstruction and other factors regarding the general condition of the patient, balloon dilatation may not be the preferred method for reestablishing the initial integrity of the artery. In fact, balloon dilatation can result in dissection of the artery wall. Other treatment methods for consideration include thrombolysis, atherectomy and laser ablation. Since balloon dilatation is not always the preferred procedure for reestablishing the flow of blood through an artery, it is essential that there be a method for examining the damage or obstruction. Having the capability to evaluate, among other things, the extent of artery disease and the length and eccentricity of a lesion allows a physician to choose the most effective method of treatment.
There are several known methods for examining an obstruction or stenosis for the purpose of evaluating the correct procedure for treatment. One such procedure, known as angiography, involves the examination of the obstructed blood vessel by radiography. Essentially, a radiopaque substance is introduced into a patient through the obstructed artery. With the aid of a fluoroscope, X-rays are used to examine the path of the radiopaque dye as it travels through the artery to the stenosis. A two-dimensional vision of the obstruction or stenosis is produced on the fluoroscope screen by the interaction of the X-rays with the radiopaque dye. A doctor may then examine this two-dimensional image for evaluating treatment.
Another method for imaging a lesion or stenosis in preparation of a revascularization procedure is through the use of intravascular ultrasound. The intravascular ultrasound also provides a two-dimensional cross-sectional image of the obstructed artery for examining the stenosis therein. With software enhancements, computer generated 3-D images can be generated but image quality is poor and the system cost is high.
Alternatively, European Patent Application 0289021 (Samson et al.) discloses another method of imaging, employing a plurality of optical fibers. The optical fibers are attached to a distal end of a catheter which is introduced into the obstructed artery. The optical fibers are positioned proximate to the obstruction to record and transmit an image of the obstruction so that it may be examined by a physician. This system requires the stoppage of blood flow and the introduction of clear saline into the artery for imaging. Imaging can therefore only be done for a short time and the system is difficult to pass through a tortuous coronary artery.
Although, several imaging systems have been described, there has been a continuing need to provide a simple, easy to use three-dimensional imaging system for the purpose of ascertaining the configuration of a cavity or lumen within a body. In particular, there is a need for such an imaging system for vascular applications to learn the configuration of an artery having an obstruction therein for the purpose of proposing and assessing treatment therefor. It would be advantageous if such an imaging system were available that is relatively easy to manufacture at a low cost and did not require capital support equipment.